Gender/Race involved. Hypertrophic pyloric stenosis (hps) is more common in boy babies & white babies. There is a 1 in 300 chance of a white baby boy developing hps. It is 5 times more common in boys than girls & 5 times more common in whites than blacks. Therefore, it is most commonly seen in white baby boys & least commonly seen in black baby girls.
Low. The classic description is the first male born. Of course this is not always the case. There are certainly family histories of several generations having children with pyloric stenosis, but pyloric stenosis itself is not very common. We see about 1-2 every 1-2 years in my practice or less.
Suspected causes. Causes are unknown, but some genetic and environmental factors probably. Higher rates among certain families and offspring of mothers who had pyloric stenosis. Pyloric stenosis occurs more often in males than in females. Early antibiotic use in infants and during pregnancy of mothers may play role.3 out of 1, 000 babies in US.4 x more in 1st born males. If in parent then infant 20% chance.